Fuse plug



` May 23, 1933. s, l SNEn-:RSQN `1,911,095

FUSE PLUG Filed July 25 1932 MW IVI l, pq VIHIINH "auguran-'u he I Jen tot ,Jhmuelllhelezsvu j E By ttglyugy Patented May 23, 1933 UNITED STATES PATENT OFFICE SAMUEL L. BNEIEBSON, 0F BOXBUBY, HASBACHUSETTS,IAS8IGNOB T0 ROYAL ELECTRIC COMPANY, INCORPORATED, 0l AVON, MASSACHUSETTS, A CORPORATION 0F MASSA- CIIUSETTS FUSE PLUG Application led Illy 25,

My present invention relates to lug fuses and particularly to vthat class o fuses. lin which there is a transparent viewing portion or window through which the fuse strip or other art of the interior may be inspected.

Such) transparent port-ions were originally provided as with the old mica disc so that the condition of the fuse strip could be ascertained and so that when a fuse was burned out its condition would be readily apparent.

My Ainvention contemplates atnovel plug fuse providing for such a viewing portion and also providing certain other features of great convenience and advantage.

One of the difficulties frequently ex erienced with these plugs has been that o the identity of plugs of different .fusing capacities. It is, of course, convenient in manufacture and in use that the plugs and plug parts be interchangeable, It is also of great importance that plugs of different capacities be distinguishable one from another so that the lug of proper capacity can be picked out or use.

As illustrative of my general concept and as indicating specific examples of importance, I have shown characteristic types in the accompanying drawing. In the drawing in which like reference characters are applied as used in the specification r Fig. I is a central vertical section ol a plug in accordance with my Iinvention.

Fig. II is a similar view showing a mod1- lied relation of stri to disc.

Fig. III and Fig. IV are fragmentary views of variant forms.

Fig. V is a section similar to Fig. showing a mica or like window installation.

Fig. VI is a plan ,indication of a characteristic disc.

Fig. VII is an edge view of the same..

Fig. VIII is an elevation of the plug with to member removed.

Tig. IX a characteristic end view of a plug showing the viewing window, and

Fig. X a plan view of the disc.

In the illustration and description I have deliberately utilized as illustrative common types of structure as these are most easily 1982. Serial No. 624,408.

understood and most immediately available for the benefit of the public as familiar and generally accepted. j

Such plugs generally consist of a base portion 1 (see Fig. I) of porcelain, glass or the like and are molded or otherwise adapted to be seated in a plug socket. Such plug por tions usually have a formed or spun shell of metal having threaded or like engagin means as indica-ted at 2 which protects an takes the wear from the vitreous or other non-conductive material of the base member l, and clamps the parts together.

The top or upper member 3 (as shown in Fig. II) may be variously constructed. As shown in Fig. I, it is an integral and usually vitreous element having a viewing portion window or pane 4. Through this the interior of the plug may be inspected or checked.

The base 1 has a c lindrical or tubular portion 5. This exten s from a base shoulder l1 upwards, in assembly, towards the top Window or viewing portion suoli as is indicated at 4 (Fig. I). It is notched as at l5 to receive the fuse strip and acts as a vent.

The fusible strip consists of a shank 7 suitably connected as at 8 in a contact point 9. Its fusible portion includes, as shown, the usual notches 10. This portion which continues as at ll, and is rebent at 12 is finally anchored and made a terminal as at 13, where it is clamped by the shell 2.

The internal support and use backing consists of a disc '14 of fibre or like insulating material. This is preferably at least modiliable by heat so ,that any change can be observed if the plug is blown out and may have an impregnation deconiposable or modifiable by heat so that the condition of the fusion will be apparent.

The tubular extension 5 of the base l affords an internal chamber for expansion and insulation. At its upper end at the terminal edge it supports the disc 14.- which bridges the internal chamber in substantially parallel relation to the window portion of the top member 3. The disc 14 in turn suports and combines with the fusible strip I) to forma unit. The assembly is disposed in such a combination directly below the viewing portion or window of the top member 3 as indicated at 4, in Fig. I, so as to be easil seen through it.

As s own in Fi I, the strip 7 is bent directly across the dise 14 as at 17 then bent downwardly as at 11 as before described. As indicated in Fig. II, the strip 7 may penetrate such a disc as 14a to be brought across and down as before described.

In Fig. III I have shown the strip 7 as making a double penetration of a dise 14o while in Fig. IV a reverse bend and penetration of a disc 140 is shown.

The Viewing portion may be variously constructed. Heretofore trans arent or semitransparent windows of mica or the like have been used so that it could be seen if the plug had been blown but plugs in accordance with my concept offer many additional advantages.

As shown in Fig. V the top member 3a is of the same general construction as in Fig. I, but instead of having an integral window it is shouldered to clamp an independent disc 4a of mica or material of like properties to overlie the disc 14 as described, which will be visible therethrough.

The member 14 is as shown preferably a circular disc but may be of any shape, material or color. As shown, it has a tab consisting of a tail 14l and an overfold 142. The tail 141 and ovcrfold 14* enclose and hold the downwardly bent portion 11 of the fuse strip. This insulates and cushions it when it is clamped in the plug and in turn holds the disc 14 and the fuse strip in proper diametrie position and in proper relation to the window or viewing area of the plug.

@ne of the primary advantages of the disc 14 is that it provides a mount for the fuse strip. This is of convenience in assembly and important in use. This simple means affords a medium of information as to the number of the plug for selection in use, but also the condition of the plug. The discs carry suitable data as to size, fusion point or other visible identification data or color which can be plainly seen through the win dow or viewing portion and as such identitication can be made as large or conspicuous as desired, no magnification and not even perfect transparency is necessary. If desired the disk may have a transverse corrugation or channel therein as shown at 15 in Figures VI, VII and X within which the fuse strip may lie.

The tab is preferably formed on the disc 14 but may be a separate or independent insulating or cushioning member with or without the disc which takes upthe heat expan sion and shock of fusion and protects the glass against shattering.

Vif hat I therefore claim and desire to secure by Letters Patent is 1. A plug fuse having a top member provided with a. window portion, a fusible strip beneath said window, a fibre disc underlying said fuse, the fuse being in viewable position relative to said window, said disc having a marginal tab overfolded on the fuse end at the side of the fuse member and held thereby against dislodgement.

2. A plug fuse having a top member of transparent material provided with a substantially clear window portion, a fusible strip beneath said window portion, a libre disc underlying said fuse and presenting visible identification when the fuse is viewed through said window, said disc having a marginal tab overfolded on the fuse end at the side of the fuse member and held thereby against dislodgement.

3. A plug fuse comprising a top member provided with a window portion, and a base member interengaged therewith, a fuse strip having a fusing point transversely of and visible through said window portion and a longitudinal portion between the interengaged top and base members, and a shield strip embracing the longitudinal portion of the fuse strip between the two plug niembers whereby the fuse strip is protectively iuterlocked in the plug assembly.

4. A plug fuse comprising a top member provided with a window portion, and a base interengaged therewith, a fuse strip having a fuse point transversely of and Visible through said window portion and a longitudinal portion between the interengaeed top and base members, and a eompressible insulation piece embracing the longitudinal portion of the fuse strip between the two plug members whereby the fuse strip is yieldably interlocked in the plug assembly.

5. A plug fuse comprising a top member provided with a window portion and a base member intel-engaged therewith, a fuse strip visible through said window portion and extending between said top and base members, and sheet insulating material wrapped about and enclosing said strip where it extends between said top and base members.

6. A fuse having a body member provided with a window portion, a fuse strip within said body member, a sheet material piece within said body member back of said window portion apertured for said strip to be passed'therethrough, said strip having a portion intermediate its ends visible through said window portion and its ends extended through said piece to the opposite side thereof. l

7. A fuse comprising a top member provided with a window portion and a base engaged with said top member to define therewith an internal chamber, said base having a central terminal extending therethrough, a threaded metallic shell uniting said meinbers, a fuse strip within said chamber united at opposite ends to said terminal and shell respectively, and a sheet material piece WithinA said chamber and back of sald window portion apertured for said strip to be passed therethrough, a portion of sald strip intermediate its endsbeing positioned visible throu h said window portion and the remaimer of said strip lying back of said piece.

8. A fuse having a body member provided with a window portion, a sheet material piece back of said window portion and having a pair of spaced perforations therethrough, and a fuse strip extending through said perforations and presenting a portion intermediate its length between sald perforations extendin across said piece and visible through sai window portion.

9. A fuse having a body member provided with a window portion, a sheet material piece back of said windowportion within said body member and havinga channel therein, and a fuse strip lying in said channel and extending transversely of said window -portion.

10. A fuse comprising aitop member provided with a window portion and a base engaged with said to member to define therewith an internal c amber, a sheet ma terial piece in said chamber substantially paralle to said Window portion and having a pair of spaced perforations therethrough,

and a fuse strip within said chamber extending through said perforations and presenting a portion intermediate its len h between said perforations and visible t rough said window portion.

In testimony whereof I affix m` signature.

SAMUEL L. SNE ERSON. 

